Objective:

This case describes a rare case of cerebrospinal fluid (CSF) culture-positive central nervous system (CNS) mycobacterium avium complex (MAC) infection and highlights the importance of biopsy for diagnosis.

Background:

Disseminated MAC infection usually develops in immunocompromised patients whose CD4 count is below 50 cells/µl. There have been many reported cases of disseminated and CNS MAC infections. However, MAC culture positivity from CNS is very uncommon. Here, we present the rare case of CNS MAC infection with multiple ring-enhancing lesions, who was later found to have primary CNS lymphoma.

Design/Methods:

Case report

Results:

A 32-year-old Hispanic male was originally diagnosed with HIV and cryptococcal meningitis in 2017 with an initial CD 4 count < 5 cells/µl and viral load of 148,513 copies/ml. He responded well to initial treatment with antifungal and viral suppression, however he was lost to follow-up over the next several years. In early 2022, he was diagnosed with disseminated MAC infection with colitis, lymphadenitis, and positive bone marrow cultures. Two months later, he presented again with headaches and confusion despite appropriate MAC treatment. MRI of the brain revealed multiple ring-enhancing lesions throughout bilateral cerebral hemispheres. CSF was positive for MAC on culture. With negative toxoplasma serologies, the ring-enhancing lesions were initially assumed to be due to the MAC infection. However, worsening MRI findings led to a brain biopsy of a prominent right frontal lesion. Pathology revealed diffuse large B-cell lymphoma, EBV-positive, non-germinal center subtype. He underwent chemotherapy with high dose methotrexate. He was recovering, but he became ill with aspergillus pneumonia after a recent COVID-19 infection and passed away.

Conclusions:

This is a unique case of a patient with CNS MAC infection with CSF culture positivity, who then was found on biopsy to have primary CNS lymphoma. It demonstrates the importance of obtaining tissue biopsy for diagnosis.